JP3955055B2 - Electromagnetic fuel injection valve - Google Patents

Description

  The present invention relates to an electromagnetic fuel injection valve, and in particular, a magnetic cylinder constituting a part of a valve housing having a valve seat at a front end portion is connected to a front portion of a cylindrical fixed core via a coaxial nonmagnetic cylinder. A flange portion that is coupled and projects radially outward from the rear end of the fixed core, is formed in a cylindrical shape having an end wall on one end side, and both ends are magnetically connected to the magnetic cylindrical body and the flange portion. A coil assembly that surrounds the rear portion of the magnetic cylinder, the non-magnetic cylinder, and the fixed core is housed in a solenoid housing that includes a coil case coupled to the coil case, and is coaxial with the rear end of the fixed core. A fuel filter is attached to the rear portion of the inlet cylinder that is integrally connected to form a fuel passage, and is made of a synthetic resin that integrally has a power receiving coupler that faces a power receiving side connection terminal connected to the coil of the coil assembly. Resin In part, relates to an electromagnetic fuel injection valve at least the front and the solenoid housing of the inlet tube is covered.

Such an electromagnetic fuel injection valve is already known from, for example, Patent Document 1.
JP 2004-76700 A

  By the way, the resin molded part of the electromagnetic fuel injection valve disclosed in Patent Document 1 is formed of a single type of synthetic resin. However, the resin molding part that covers the solenoid housing and at least the front part of the inlet cylinder is not only for the function of suppressing the emission of operating noise generated from the solenoid housing to the outside, but also for receiving power to improve the reliability of the electrical connection part. Since it is necessary to keep the strength of the coupler relatively high, it is also required to have a high strength, and a resin molded portion having a sufficient strength while being able to sufficiently suppress operating noise, It is difficult to form with a single kind of synthetic resin as disclosed in Patent Document 1.

  Therefore, the applicant of the present invention is a resin formed by two-layer molding of a first resin molding layer whose strength is increased by mixing glass fiber and a second resin molding layer which suppresses transmission of operating sound by not mixing glass fiber. An electromagnetic fuel injection valve that constitutes a molding part has already been proposed (Japanese Patent Application No. 2004-53691).

  However, in the above proposed technique, the thickness of the first and second shape layers is set larger than the thickness of the portion near the fixed core of the inlet tube that is coaxially connected to the rear end of the fixed core. It is difficult to say that the rigidity of the connecting portion to the fixed core is sufficient, and due to insufficient rigidity, an impact caused by the opening / closing operation of the valve body in the valve housing is caused by the first resin molding layer via the inlet tube. This causes the fuel distribution pipe connected to the power receiving coupler and the inlet tube to vibrate due to the propagation by the glass fiber in the first resin molding layer, and in particular causes high frequency operation noise.

  The present invention has been made in view of such circumstances, and is intended to improve the rigidity of the connecting portion of the inlet cylinder to the fixed core so that the generation of operating noise can be effectively reduced particularly in a high-frequency region. An object of the present invention is to provide a fuel injection valve.

  In order to achieve the above object, the invention according to claim 1 is characterized in that a magnetic cylindrical body constituting a part of a valve housing having a valve seat at a front end is formed of a cylindrical fixed core via a coaxial nonmagnetic cylindrical body. A flange portion coupled to the front portion and projecting radially outward from the rear end of the fixed core; a cylindrical shape having an end wall on one end side; and both ends of the magnetic cylindrical body and the flange portion And a coil assembly surrounding the rear portion of the magnetic cylindrical body, the non-magnetic cylindrical body and the fixed core is housed in a solenoid housing including a coil case magnetically coupled to the rear of the fixed core. A composite having a power receiving coupler for integrally receiving a power receiving side connection terminal connected to a coil of the coil assembly, wherein a fuel filter is attached to a rear portion of an inlet cylinder coaxially and integrally connected to an end to form a fuel passage. Resin In an electromagnetic fuel injection valve in which at least a front portion of the inlet tube and the solenoid housing are covered by a resin molding portion, the resin molding portion constitutes a coupler main portion that forms a skeleton portion of the power receiving coupler, and a glass fiber A first resin molding layer formed of a synthetic resin mixed with a second resin molding layer formed of a synthetic resin that covers the first resin molding layer and excludes glass fibers. In the portion of the inlet cylinder on the fixed core side, when the thickness of the first resin molding layer is t1, the thickness of the second resin molding layer is t2, and the thickness of the inlet cylinder is t3, t1 <t3 ≦ t2 It is characterized by being set to.

  In addition to the configuration of the invention of claim 1, the invention of claim 2 is such that the front half of the inlet tube on the fixed core side is covered with the first resin molding layer, and the second resin molding layer is It is formed so as to directly cover the inlet tube behind the portion covered with the first resin molding layer.

  According to a third aspect of the present invention, in addition to the configuration of the first or second aspect of the invention, the flange portion at the rear end of the fixed core and the connecting portion of the inlet tube have a saddle curved surface recessed inwardly. Is formed.

  Furthermore, in addition to the structure of the invention according to any one of claims 1 to 3, the invention according to claim 4 is such that the fixed core, the flange portion, and the inlet cylinder have a circular cross section in any axial direction. Thus, it is formed by integral grinding.

  According to the first aspect of the present invention, the resin molding portion has a two-layer structure including the first resin molding layer and the second resin molding layer, and the first resin molding layer is formed of a synthetic resin mixed with glass fibers. Therefore, it is possible to give the resin molded part the strength that can ensure the reliability of the electrical connection part by forming the coupler main part forming the skeleton part of the power receiving coupler with the first resin molded layer. Since the 2nd resin molding layer which covers the 1st resin molding layer is formed with the synthetic resin which excluded mixing of glass fiber, it becomes possible to control generation of operation sound effectively. Moreover, since the thickness of the inlet cylinder is larger than the thickness of the first resin molding layer in the portion of the inlet cylinder on the fixed core side, the rigidity of the connecting portion of the inlet cylinder to the fixed core is increased, and the first While suppressing vibration transmission to the resin molding layer, vibration transmission by the glass fibers contained in the first resin molding layer can be suppressed by reducing the thickness of the first resin molding layer, and generation of operating noise can be suppressed. In particular, it can be effectively suppressed in the high frequency region. In addition, since the thickness of the second resin molding layer that does not include glass fibers is larger than the thickness of the first resin molding layer and equal to or greater than the thickness of the inlet tube, vibrations are effectively absorbed by the second resin molding layer. And generation | occurrence | production of an operating sound can be suppressed further.

  According to the invention described in claim 2, by suppressing the propagation of vibration and suppressing the generation of operating noise more effectively by reducing the portion covered with the first resin molding layer containing glass fiber as much as possible. it can.

  According to the invention described in claim 3, the rigidity of the connecting portion of the inlet cylinder to the fixed core is further increased, and the axial direction of the fuel injection valve can be shortened, while the inlet cylinder is moved to the first resin molding layer side. It is possible to suppress the propagation of the vibration of the vibration, and more effectively suppress the generation of the operating sound particularly in the high frequency region.

  Furthermore, according to the invention described in claim 4, the rigidity of the parts can be further increased by integrally grinding the fixed core, the flange portion, and the inlet cylinder, and further, since any cross section in the axial direction is circular, additional machining is required. This is unnecessary and is advantageous in terms of cost.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below based on examples of the present invention shown in the accompanying drawings.

  1 to 3 show a first embodiment of the present invention, FIG. 1 is a longitudinal sectional view of an electromagnetic fuel injection valve, and FIG. 2 is a bending strength of a liquid crystal polymer mixed with glass fiber and a thermoplastic polyester elastomer. FIG. 3 is a diagram showing a change in sound pressure with frequency.

  First, in FIG. 1, an electromagnetic fuel injection valve for injecting fuel into an engine (not shown) is a spring-biased valve in a valve housing 9 having a valve seat 8 at a front end in a direction in which the valve seat 8 is seated. A solenoid in which a valve operating part 5 in which a body 10 is accommodated and a coil assembly 11 capable of exerting an electromagnetic force for driving the valve body 10 on the side to be separated from the valve seat 8 are connected to the valve housing 9 Synthetic resin that integrally includes at least the solenoid unit 6 having a power receiving coupler 40 that faces the solenoid unit 6 housed in the housing 12 and the power receiving side connection terminals 38 connected to the coil 29 of the coil assembly 11. And a resin molded part 7 made of metal.

  The valve housing 9 includes a magnetic cylinder 13 formed of a magnetic metal and a valve seat member 14 that is liquid-tightly coupled to the front end of the magnetic cylinder 13. The valve seat member 14 is welded to the magnetic cylindrical body 13 with its rear end fitted to the front end of the magnetic cylindrical body 13, and the valve seat member 14 opens to the front end surface thereof. A fuel outlet hole 15, a tapered valve seat 8 connected to the inner end of the fuel outlet hole 15, and a guide hole 16 connected to the rear end large diameter portion of the valve seat 8 are provided coaxially. A steel plate injector plate 18 having a plurality of fuel injection holes 17 leading to the fuel outlet hole 15 is welded to the front end of the valve seat member 14 in a liquid-tight manner.

  A movable core 20 constituting a part of the solenoid unit 6 is slidably fitted to a rear portion in the valve housing 9, and the valve seat is formed at a front end of a valve shaft 21 integrally connected to the movable core 20. A valve body 10 that can be seated on the base 8 and close the fuel outlet hole 15 is formed integrally. In the movable core 20, the valve shaft 21 and the valve body 10, a through hole 22 communicating with the inside of the valve housing 9 is formed coaxially with a bottomed shape with the front end closed.

  The solenoid unit 6 includes the movable core 20, a cylindrical fixed core 23 that faces the movable core 20, and a return spring 24 that exerts a spring force that biases the movable core 20 away from the fixed core 23. The coil is disposed so as to surround the rear portion of the valve housing 9 and the fixed core 23 while enabling to exert an electromagnetic force that attracts the movable core 20 toward the fixed core 23 against the spring force of the return spring 24. An assembly 11 and a solenoid housing 12 surrounding the coil assembly 11 so that the front end portion is connected to the valve housing 9 are provided.

  The rear end of the magnetic cylinder 13 in the valve housing 9 is coaxially coupled to the front portion of the fixed core 23 via a nonmagnetic cylinder 25 formed of a nonmagnetic metal such as stainless steel. The rear end of the cylindrical body 13 is butt welded to the front end of the nonmagnetic cylindrical body 25, and the rear end of the nonmagnetic cylindrical body 25 is a fixed core in a state where the front portion of the fixed core 23 is fitted to the nonmagnetic cylindrical body 25. 23 is welded.

  A cylindrical retainer 26 is fitted to the fixed core 23 and fixed by caulking, and the return spring 24 is interposed between the retainer 26 and the movable core 20. A ring-shaped stopper 27 made of a non-magnetic material is provided from the rear end surface of the movable core 20 on the inner periphery of the rear end portion of the movable core 20 so as to prevent the movable core 20 from coming into direct contact with the fixed core 23. It is fitted and fixed so that it protrudes slightly to the side. Further, the coil assembly 11 is formed by winding a coil 29 around a bobbin 28 surrounding the rear portion of the valve housing 9, the nonmagnetic cylindrical body 25 and the fixed core 23.

  The solenoid housing 12 has a circular end wall 31a opposite to the end of the coil assembly 11 on the side of the valve actuating portion 5 at one end, and has a cylindrical shape surrounding the coil assembly 11 and is formed of a magnetic metal. 31 and a flange portion 23a projecting radially outward from the rear end portion of the fixed core 23 and facing the end portion opposite to the valve operating portion 5 of the coil assembly 11, 23 a is magnetically coupled to the other end of the coil case 31. In addition, a fitting cylinder portion 31b for fitting the magnetic cylindrical body 13 in the valve housing 9 is coaxially provided on the inner periphery of the end wall 31a in the coil case 31, and the solenoid housing 12 has its fitting cylinder portion. By fitting the valve housing 9 to 31 b, the valve housing 9 is connected, and one end of the coil case 31 is magnetically coupled to the magnetic cylindrical body 13.

  A cylindrical inlet cylinder 32 is integrally and coaxially connected to the rear end of the fixed core 23, and a fuel filter 33 is attached to the rear part of the inlet cylinder 32. Moreover, the inlet tube 32, the retainer 26, and the fixed core 23 are provided with a fuel passage 34 that communicates with the through hole 21 of the movable core 20 coaxially.

  The resin molding part 7 fills not only the solenoid housing 12 and the coil assembly 11 of the solenoid part 6 but also the gap between the solenoid housing 12 and the coil assembly 11, and at least a part of the valve housing 9 and the inlet cylinder 32. The terminal boss portion 36 formed integrally with the bobbin 28 of the coil assembly 11 is disposed outside the solenoid housing 12 in the coil case 31 of the solenoid housing 12. The notch 35 is provided.

  The resin molding portion 7 is integrally provided with a power receiving coupler 40 that forms a recess 39 that faces power receiving side connection terminals 38 continuous to both ends of the coil 29 in the coil assembly 11. The base ends of the connection terminals 38 are embedded in the terminal boss portion 36, and the coil ends 29a of the coils 29 are electrodeposited on the power receiving side connection terminals 38.

  By the way, the resin molding portion 7 includes a first resin molding layer 41 that forms a coupler main portion 40a that forms a skeleton of the power receiving coupler 40, and an outer peripheral portion of the power receiving coupler 40 from the middle portion of the power receiving coupler 40. The second resin molding layer 42 covering the first resin molding layer 41 so as to be exposed is formed in two layers. In this embodiment, the entire solenoid portion 6, the rear portion of the valve housing 9, and the inlet port are formed. A part of the cylinder 32 is covered with the first resin molding layer 41, and the second resin molding layer 42 covering the first resin molding layer 41 is formed from the middle part of the power receiving coupler 40 on the tip side of the first resin molding layer 41. The outer surface is exposed, and the front end portion of the first resin molding layer 41 is slightly exposed. In addition, the front half of the inlet cylinder 32 on the fixed core 23 side is covered with the first resin molding layer 42, whereas the second resin molding layer 42 is behind the portion covered with the first resin molding layer 41 and the inlet cylinder. 32 is directly covered.

  An annular protrusion 45 that bites into the first resin molding layer 41 is integrally provided on the outer surface near the fixed core 23 of the inlet cylinder 32, and the second resin molding layer 42 is formed on the outer surface near the rear of the inlet cylinder 32. An annular groove 46 is provided for engaging the end.

  The first and second resin molding layers 41 and 42 are formed of different synthetic resins, whereas the first resin molding layer 41 is formed of a synthetic resin mixed with glass fibers, for example, a liquid crystal polymer. The second resin molding layer 42 is formed of a synthetic resin having a bending strength smaller than that of the first resin molding layer 41. The first resin molding layer 41 is made of, for example, a liquid crystal polymer mixed with glass fibers. The formed second resin molding layer 42 is formed of a synthetic resin from which glass fibers are not mixed, for example, a thermoplastic polyester elastomer that is a trade name Hytrel (USA DuPont).

  By the way, the relationship between the bending strength when the entire resin molded part 7 is formed of a liquid crystal polymer mixed with 35% glass fiber, for example, and the operating sound pressure peak generated from the resin molded part 7 is shown by a point A in FIG. The liquid crystal polymer has a function of relatively suppressing the transmission of operation sound and is also highly rigid. On the other hand, when the entire resin molded part 7 is formed of a thermoplastic polyester elastomer that excludes glass fibers, the generation of operating noise can be effectively suppressed by the excellent flexibility of the thermoplastic polyester elastomer. As shown by the point B in FIG. 2, the operating sound pressure peak can be kept low although the bending strength is lower than that of the liquid crystal polymer.

  According to the present invention, the thickness of the first resin molding layer 41 is t1 in the portion on the fixed core 23 side of the inlet tube 32, in this embodiment the portion on the fixed core 23 side relative to the annular protrusion 45, and the second resin molding. The thicknesses t1, t2, and t3 are set so that t1 <t3 ≦ t2, where the thickness of the layer 42 is t2 and the thickness of the inlet tube 32 is t3.

  Further, a flange surface 23a at the rear end of the fixed core 23 and a connecting portion of the inlet tube 32 are formed with a curved surface 47 that is recessed inward, and the fixed core 23, the flange portion 23, and the inlet tube 32 are These are formed by integral grinding so that any cross section in the axial direction is circular.

  Next, the operation of this embodiment will be described. The resin molding part 7 is formed of a synthetic resin containing glass fiber so as to constitute at least the solenoid part 6 and constitute the coupler main part 40a constituting the skeleton of the power receiving coupler 40. The first resin molding layer 41 is formed of a synthetic resin that does not contain glass fiber, and the first resin molding layer 41 is exposed from the intermediate portion of the power receiving coupler 40 so that the first resin molding layer 41 is exposed. A second resin molding layer 42 covering 41 is formed by two-layer molding.

  Accordingly, the first resin molding layer 41 forms the coupler main portion 40a that covers the connection portion of the coil 29 and the power receiving side connection terminals 38 of the coil assembly 11 with the first resin molding layer 41 and forms the framework of the power receiving coupler 40. In this way, the resin molding part 7 can be given strength that can ensure the reliability of the electrical connection part. Further, since the second resin molding layer 42 covering the first resin molding layer 41 is formed of a synthetic resin not containing glass fibers, it is possible to effectively suppress the generation of operating noise, and the entire fuel injection valve. Compared with the case where the soundproof cover is used, the entire electromagnetic fuel injection valve can be made compact. Moreover, by forming two layers up to the middle portion of the power receiving coupler 40, the first resin molding layer 41 provides the strength required for the power receiving coupler 40, while the second resin molding layer 42 removes the strength from the power receiving coupler 40. The generation of the operating noise can be effectively reduced.

  Moreover, in the portion of the inlet cylinder 32 on the fixed core 23 side, the thickness t3 of the inlet cylinder 32 is larger than the thickness t1 of the first resin molding layer 41. Therefore, the rigidity of the connecting portion of the inlet cylinder 32 to the fixed core 23 is increased. To suppress vibration transmission from the inlet tube to the first resin molding layer 41, and to reduce vibration transmission by the glass fiber contained in the first resin molding layer 41 to a thickness t1 of the first resin molding layer 41. The generation of operating noise can be effectively suppressed particularly in the high frequency region. Moreover, since the thickness t2 of the second resin molding layer 42 that does not include glass fiber is larger than the thickness of the first resin molding layer t1 and equal to or greater than the thickness t3 of the inlet tube 32, the second resin molding layer 42 Vibration can be effectively absorbed and the generation of operating noise can be further suppressed.

  Further, since the flange portion 23a at the rear end of the fixed core 23 and the connecting portion of the inlet tube 32 are formed with a curved surface 47 that is recessed inward, the connecting portion of the inlet tube 32 to the fixed core 23 is formed. While further improving the rigidity and enabling the fuel injection valve to be shortened in the axial direction, the propagation of vibration from the inlet cylinder 32 to the first resin molding layer 41 side is further suppressed, and the generation of operating noise particularly in the high frequency region is further reduced. It becomes possible to suppress effectively.

  Here, the change in sound pressure due to the frequency when the connecting portion to the flange portion 23 of the inlet cylinder 32 is a right angle and the thickness t3 of the inlet cylinder 32 is smaller than the thickness t1 of the first resin molding layer 41 is shown in FIG. 3, and in accordance with the present invention, a curved surface 47 is formed in the connecting portion to the flange portion 23 of the inlet cylinder 32, and the wall thickness t 3 of the inlet cylinder 32 is the wall thickness t 1 of the first resin molding layer 41. The change in sound pressure due to the frequency when the thickness t2 of the second resin molding layer 42 is greater than or equal to the thickness t3 of the inlet cylinder 32 is shown by B in FIG. The sound pressure level can be reduced in the high frequency region by making the wall thickness t3 of the inlet tube 32 larger than the wall thickness t1 of 41 and forming the curved surface 47 at the connecting portion of the flange portion 23a and the inlet tube 32. Is clear.

  The first half of the inlet cylinder 32 on the fixed core 23 side is covered with the first resin molding layer 42, whereas the second resin molding layer 42 is behind the part covered with the first resin molding layer 41. 32 is formed so as to directly cover 32, the propagation of vibrations can be suppressed by reducing the portion covered with the first resin molding layer 41 containing glass fibers as much as possible, and the generation of operating noise can be more effectively suppressed. it can.

  Further, by integrally grinding the fixed core 23, the flange portion 23a, and the inlet cylinder 32, the rigidity of the parts can be further increased, and since any cross section in the axial direction is circular, no additional work is required, resulting in cost reduction. It will be advantageous.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various design changes can be made without departing from the present invention described in the claims. It is.

It is a longitudinal cross-sectional view of an electromagnetic injection valve. It is a figure which shows the relationship between the bending strength and the working sound pressure peak of the liquid crystal polymer and thermoplastic polyester elastomer with which glass fiber was mixed. It is a figure which shows the sound pressure change by a frequency.

Explanation of symbols

DESCRIPTION OF SYMBOLS 7 ... Resin molding part 8 ... Valve seat 9 ... Valve housing 11 ... Coil assembly 12 ... Solenoid housing 13 ... Magnetic cylindrical body 23 ... Fixed core 23a ... Flange Part 25: Non-magnetic cylindrical body 29 ... Coil 31 ... Coil case 31a ... End wall 32 ... Inlet tube 33 ... Fuel filter 34 ... Fuel passage 38 ... Power receiving side Connection terminal 40... Power receiving coupler 40 a... Coupler main portion 41... First resin molding layer 42.

Claims (4)

  A magnetic cylinder (13) constituting a part of a valve housing (9) having a valve seat (8) at the front end is disposed in front of a cylindrical fixed core (23) via a coaxial nonmagnetic cylinder (25). And a flange portion (23a) projecting radially outward from the rear end of the fixed core (23), and an end wall (31a) on one end side and formed in a cylindrical shape, and both ends are In the solenoid housing (12) composed of the magnetic cylinder (13) and the coil case (31) magnetically coupled to the flange portion (23a), the rear part of the magnetic cylinder (13), A coil assembly (11) surrounding the nonmagnetic cylindrical body (25) and the fixed core (23) is accommodated, and is coaxially and integrally connected to the rear end of the fixed core (23) to be connected to the fuel passage (34). At the rear of the inlet tube (32) forming the fuel fill (33) and a synthetic resin resin molding part (7) integrally including a power receiving coupler (40) facing the power receiving side connection terminal (38) connected to the coil (29) of the coil assembly (11). ), In the electromagnetic fuel injection valve in which at least the front portion of the inlet tube (32) and the solenoid housing (12) are covered, the resin molding portion (7) has a skeleton portion of the power receiving coupler (40). The first resin molding layer (41) formed of a synthetic resin mixed with glass fibers while constituting the coupler main part (40a) to be formed, and the glass fibers mixed so as to cover the first resin molding layer (41) The second resin molding layer (42) formed of a synthetic resin that excludes the thickness of the first resin molding layer (41) at a portion of the inlet cylinder (32) on the fixed core (23) side. T1, second resin The thickness of the form layer (42) t2, the wall thickness of the inlet tube (32) when the t3, an electromagnetic fuel injection valve, characterized in that it is set to t1 <t3 ≦ t2.   The front half of the inlet tube (32) on the fixed core (23) side is covered with the first resin molding layer (41), and the second resin molding layer (42) is the first resin molding layer (41). The electromagnetic fuel injection valve according to claim 1, wherein the inlet fuel cylinder (32) is formed directly behind the portion to be covered.   The flange portion (23a) at the rear end of the fixed core (23) and the connecting portion of the inlet tube (32) are formed with a curved surface (47) recessed inward. Item 3. The electromagnetic fuel injection valve according to Item 1 or 2.   The said fixed core (23), the said flange part (23a), and the said entrance pipe | tube (32) are formed by integral grinding so that all the cross sections of an axial direction may be circular. The electromagnetic fuel injection valve in any one of -3.

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